Multiple cylinder stirling engine with equalized high pressure in cell cylinders

ABSTRACT

In a multiple cylinder Stirling engine that has higher and lower pressure gas chambers separated by pistons in each cylinder the pressure in the various cylinders is equalized by a valve assemblage to correct the effects of any leakage through the pistons. The valve assemblage causes the highest pressure portions of the cylinders to equalize at the lowest maximum cycle pressure in any cylinder.

United States Patent [1 1 [111 3,807,176

Hakansson Apr. 30, 1974 [54] MULTIPLE CYLINDER STIRLING ENGINE 2,794,3156/1957 Meijer 60/24 WITH EQUALIZED HIGH PRESSURE IN 2,867,973 1/1959Meyer 60/24 CELL CYLINDERS 3,458,995 I 8/1969 l-lefiner et al 60/24 [75]Inventor: Sven Anders Samuel Hakansson, FOREIGN PATENTS OR APPLICATIONSMalmo Sweden 630,800, 6/1936 Germany 60/24 [73] Assignee:Kommanditbolaget United Stirling (Sweden) AB & Malmo, 7 PrimaryExaminerEdgar W. Geoghegan Sweden Assistant Examiner-H. Burks, Sr. 22Fil June 23 1972 Attorney, Agent, or Firm-Laurence R. Brown, Esq.

211 Appl. No.: 265,538

57 ABSTRACT 30 Forei A lieation Priorit Data gn pp y In a multiplecylinder Stirling engine that has higher June 30, 1971 Great Britain30619/71 and lower pressure g Chambers separated y pistons in eachcylinder the pressure in the various cylinders is 8|. equalized by avalve assemblage to Correct the effects [58] d 360/24 of any leakagethrough the pistons. The valve assemie 0 re blage causes the highestpressure portions of the cylim ders to equalize at the lowest maximumcycle pressure [56] References Cited in any cylinder.

UNITED STATES PATENTS 2,746,241 5/1956 Dros et al. 60/24 4 Claims, 1Drawing Figure a 5 1| ,3 II H Y 21 2e 29- an 25 37 as 41 31. a

EQUALIZED HIGH PRESSURE IN CELL CYLINDERS This invention relates to amulti-cylinder doubleacting Stirling cycle engine of the kind (hereincalled the kind defined") in which each cylinder contains a piston whichseparates a low-temperature working space from a high temperaturechamber in the cylinder and which separates from each other two workinggas charges employed in two different working'cycles, thus in the eventof some working gas leaking past one of the pistons it may occur thatduring the working cycles of one of'the working gas charges the meaneffective pressure is higher than that obtained during the cycles of theother working gas charges. A higher mean pressure results a higheroutput from one or more of the cylinders and thus there is an unevenpower distribution among the cylinders of the engine. For reasons ofsafety the governing of the engine total power output must be based uponthe output from that one of the engine cylinders having the largestpower output, and consequently an uneven power distribution will resultin a decrease of the total output'of the engine.

Therefore it is an object of the present invention to avoid differentmean effective pressures in the separate working gas charges of anengine of the kind defined.

According to the present invention there is provided an engine of thekind defined wherein the low temperature working space of each cylinderis connected to two conduits the first one of which is provided with anonreturn valve allowing flow of gas only in the direction into saidworking space, the second one of which is provided with a non-returnvalve allowing flow of gas only in the direction out from said workingspace, all of the said fist conduits being connected to a common valvechamber provided with a plurality of valve-governed inlet openings eachof which is connected to one of said second conduits receiving gas fromthe respective low temperature working space.

The scope of the monopoly sought is defined in the claims hereinafter,and how the invention may be put into practice is described in moredetail with reference to the accompanying drawing which showsschematically in vertical section a four-cylinder, double-actingStirling cycle engine according to the invention.

The engine shown comprises four cylinders 14 each accommodatingareciprocating respective piston -8 provided with a respective pistonrod 9-12.

Each piston 58 divides the respective cylinder 1-4 in which it isarranged into two chambers of variable volumes an upper chamber and alower chamber. The upper chamber 13 of the cylinder 2. is connected withthe lower chamber 14 of the cylinder 1. Similarly the upper chambers 15,17 and 19 of the cylinders 3, 4 and 1 are connected with the lowerchambers 16, 18 and 20 of the cylinders 2, 3 and 4 respectively. Theconnections are established through pipes and units 21-24 each includinga regenerator and a cooler. The upper chambers 13, 15, 17 and 19 areheated by heating devices (not shown) and are thus kept at a hightemperature level. The lower chambers l4, l6, 18, 20 are kept at a lowtemperature level due to the coolers in the units 2'l-24. The volumevariations of each of the upper chambers at the high temperature levelare synchronous with but phased 90 in advance of the vol nine variationsof the lower chamber with which it is connected. The engine shown willcontain four separate working gas charges, the separation being effectedby the pistons. The working gas is hydrogen or helium at a high pressurelevel which during operation will vary, for example, between 225 andbars.

The lower chambers 14, 16, 18,, 20 areconnected to a pipe 25 through apath containing a non-return valve allowing flow of gas only in thedirection into the respective lower chamber. In the drawing only thenonreturn valve 26 between the chamber 20 and the pipe 25 has areference numeral. The lower chambers l4, l6, l8 and 20 are alsoconnected to individual pipes 27, 28, 29 and 30 respectivelythroughnon-return valves allowing flow of gas only in the direction out of thelower chambers. Only the valve 31 governing the passage between thechamber 20 and the pipe 30 has a reference numeral.

The pipes 25 and 27-30 are all connected to a valve assemblage 32. Thesaid valve assemblage 32 contains a chamber 33 communicating withthepipe 25 and thus containing workings at the minimum pressure level.

. The chamber 33 contains a two-armed lever 34 normally balanced byequal forces transmitted to its ends through rods 35 and 36. The rod 35carries a twoarmed lever 37 balanced by equal forces from expansiblechambers 38 and 39 communicating with the pipes 27 and 28 respectively.

The ends of the lever 37 are located adjacent to valve stems of valves40 and 41 controlling a passage between the chamber 33 and the pipes27and 28 respectively. If the lever 37 is angularly displaced in avertical plane one of the valves 40 and 41 will open the connectionbetween the respective high pressure pipe 27 or 28 and the chamber 33.

The rod 36 carries a two-armed lever '42 of the same type as the lever37 and able to actuate valves for governing connections between thepipes 29 and 30 and the chamber 33.

The illustrated arrangement operates as follows:

During normal operation under constant load the gas pressure will varybetween equal levels in the four separate working gas chargesrespectively contained mainly in thecharnbers 19-20, 13l4, 15-16 and17-18. Therefore the non-return valves will not operate at all, and theminimum gas pressure will prevail in the pipe 25 while equal maximumpressures will prevail in the four pipes 27-30. g I

However, during the operation of the engine it may happen that some gaspasses a piston, for example from the chamber 14 in the cylinder 1 tothe chamber 19 in the same cylinder. Therefore the gas charge in thechambers 19-20 will be increased in quantity and give rise to a highermean effective pressure and a higher maximum pressure than the othercharges. Consequently the pressure in the pipe 30 will be greater thanthe pressure in the pipe 29" and the expansible bodies will rock thelever 42 to open the valve governing the passage between the pipe 30 andthe chamber 33. Thus excess of gas in the chambers 19-20 will bedischarged to the common chamber 33. It will be understood that in anycase of uneven pressure in the pipes 27-30 the valve assemblage 32 willcause a decrease of the highest pressure in the pipes 27-30 until thepressure in all of them is equal to that prevailing in the pipe havingthe lowest maximum cycle pressure.

The levers 34, 37 and 42 are shown to be provided each with an upwardlyextending middle section. Thus as the deviation from the neutralposition increases there is increasing resistance againstfurtherdeviation from the horizontal neutral position. Hereby opening of avalve for an excessive period is prevented. Such excessive opening wouldautomatically cause opening of the other valves and thus an undesiredshort-circuiting of the pipes 27-30 and the pipe 25.

The non-return valves 31 ensuring that the maximum cycle pressureprevails in the pipes 27, 38, 29 and 30 are designed so as to allow arestricted flow of gas in both directions. This is illustrated by arestricted passage 43 parallel to the valve 31.

The reason for this design of the valves 31 is to make it possible tolower the mean effective pressure of the gas in all the four separateworking gas cycle circuits (for regulating the power output of theengine) and retain the function of the pressure'equalising valveassemblage 32.

What we claim is:

l. A multi-cylinder double-acting Stirling cycle engine wherein eachcylinder contains a piston which separates a low-temperature workingspace from a high temperature chamber and which separates two workng gascharges employed in two different working cycles, comprising incombination, first and second conduit means connected to the lowtemperature working space of each cylinder, said'first conduit meansincluding a non-return valve allowing flow of gas only in the directioninto said working space, said second conduit means including anon-return valve allowing flow of gas only in the direction out of saidworking space, and a common valve chamber connected to all of said firstconduit means, said valve chamber having a plurality of inlets eachgoverned by a control valve each of which is connected to an individualone of said second conduit means to pass to said first conduit means gasfrom said working spaces when maximum pressures are unequal in theworking spaces, thereby equalizing the maximum pressure in all saidworking spaces.

2. An engine as defined in claim 1 including means opening each of saidcontrol valves as a function of pressure in its corresponding inletcompared with the pressure of at least one other inlet.

3. An engine as defined in claim 2 including means for operating saidcontrol valves to increase resistance as deviation from a balance ofsaid compared pressures is increased.

4. An engine as defined in claim 1 wherein said inlet control valvesinclude actuating means comprising levers operable by balancing theforces derived from the maximum gas pressures prevailing in differentcylinders.

1. A multi-cylinder double-acting Stirling cycle engine wherein eachcylinder contains a piston which separates a low-temperature workingspace from a high temperature chamber and which separates two workng gascharges employed in two different working cycles, comprising incombination, first and second conduit means connected to the lowtemperature working space of each cylinder, said first conduit meansincluding a non-return valve allowing flow of gas only in the directioninto said working space, said second conduit means including anon-return valve allowing flow of gas only in the direction out of saidworking space, and a common valve chamber connected to all of said firstconduit means, said valve chamber having a plurality of inlets eachgoverned by a control valve each of which is connected to an individualone of said second conduit means to pass to said first conduit means gasfrom said working spaces when maximum pressures are unequal in theworking spaces, thereby equalizing the maximum pressure in all saidworking spaces.
 2. An engine as defined in claim 1 including meansopening each of said control valves as a function of pressure in itscorresponding inlet compared with the pressure of at least one otherinlet.
 3. An engine as defined in claim 2 including means for operatingsaid control valves to increase resistance as deviation from a balanceof said compared pressures is increased.
 4. An engine as defined inclaim 1 wherein said inlet control valves include actuating meanscomprising levers operable by balancing the forces derived from themaximum gas pressures prevailing in different cylinders.